105 lines
3.5 KiB
C
105 lines
3.5 KiB
C
/*
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* Copyright (c) 1989 - 1993, Julianne Frances Haugh
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* Copyright (c) 1996 - 1999, Marek Michałkiewicz
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* Copyright (c) 2003 - 2005, Tomasz Kłoczko
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* Copyright (c) 2007 - 2008, Nicolas François
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the copyright holders or contributors may not be used to
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* endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <config.h>
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#ident "$Id$"
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#include <sys/types.h>
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#include <stdio.h>
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#include "prototypes.h"
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#include "defines.h"
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#include <pwd.h>
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/*
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* valid - compare encrypted passwords
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*
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* Valid() compares the DES encrypted password from the password file
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* against the password which the user has entered after it has been
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* encrypted using the same salt as the original. Entries which do
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* not have a password file entry have a NULL pw_name field and this
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* is used to indicate that a dummy salt must be used to encrypt the
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* password anyway.
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*/
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bool valid (const char *password, const struct passwd *ent)
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{
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const char *encrypted;
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const char *salt;
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/*
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* Start with blank or empty password entries. Always encrypt
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* a password if no such user exists. Only if the ID exists and
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* the password is really empty do you return quickly. This
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* routine is meant to waste CPU time.
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*/
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if ((NULL != ent->pw_name) && ('\0' == ent->pw_passwd[0])) {
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if ('\0' == password[0]) {
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return true; /* user entered nothing */
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} else {
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return false; /* user entered something! */
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}
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}
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/*
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* If there is no entry then we need a salt to use.
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*/
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if ((NULL == ent->pw_name) || ('\0' == ent->pw_passwd[0])) {
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salt = "xx";
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} else {
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salt = ent->pw_passwd;
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}
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/*
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* Now, perform the encryption using the salt from before on
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* the users input. Since we always encrypt the string, it
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* should be very difficult to determine if the user exists by
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* looking at execution time.
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*/
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encrypted = pw_encrypt (password, salt);
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/*
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* One last time we must deal with there being no password file
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* entry for the user. We use the pw_name == NULL idiom to
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* cause non-existent users to not be validated.
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*/
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if ( (NULL != ent->pw_name)
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&& (strcmp (encrypted, ent->pw_passwd) == 0)) {
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return true;
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} else {
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return false;
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}
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}
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